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GU Fuels U: How to Deal with a Derailed Race

Many races go sideways as a result of poor nutrition. Here are some tips from GU on how to get back on track.

by Brent Mann, VP of RD/Scientific Affairs, GU Energy Labs

Whether it's a bad stomach, forgetting to eat, exercising too intensely, or just letting time get away from you, there are many ways an athlete can fall behind in the nutrition department. Luckily, it is possible to turn your race around.

The first thing to think about is that you need to get some carbohydrates on board to fuel your working muscles. In order to do this, you may have to slow down in order to divert blood flow from working muscle to your gut to absorb the ingested calories. Blood flow decreases as exercise intensity increases, such that even low exercise intensities can cut gut blood flow by 50-60 percent. Poor blood flow is why athletes may have abdominal cramps and distress when trying to eat during very high intensity exercise. If you're racing at a high intensity, it's time to ingest carbohydrates, decrease your exercise intensity, and allow your gut to digest and process the nutrients. It's also important to ingest easily available carbohydrates, such as gels, which maximize carbohydrate availability compared to something like an energy bar. So while the doughnuts may sound good, stick to a rapidly absorbable energy source.

Carbohydrate, and more precisely, muscle glycogen, provides an increasingly important proportion of muscle energy expenditure during high intensity exercise. So if you are out of glycogen, the exercise intensity you can maintain is much lower. If you have bonked, and glycogen stores are running low, you will have to rely on the carbohydrates you consume to provide the fuel you need for exercise. Maximal CHO oxidation rates are approximately 1.4 g/min when ingesting multiple sources of carbohydrate during ultra-endurance exercise. The maximal rate of exogenous carbohydrate oxidation is also dependent on the type of carbohydrate you consume. Maltodextrin and fructose, for example, result in higher rates of exogenous carbohydrate oxidation compared to maltodextrin alone. This is likely due to the use of multiple gut carbohydrate transporters, which allow greater rates of carbohydrate entry into the blood than only one type of carbohydrate in isolation. So if you find yourself in a close to bonking, or in a bonked state, you should pick a carbohydrate source that maximizes total glucose entry and oxidation, which means a combination of glucose and fructose, or lactate and glucose. However, if you are totally dependent on exogenous carbohydrates intake to provide fuel for carbohydrate oxidation, you will have to slow down in order to allow this rate of carbohydrate oxidation to supply the demands of working muscle.

If you have a big descent in your race, you can also use this topographical feature to your nutritional advantage. During a descent, your exercise intensity will drop. First, this will allow your gut more blood flow to process ingested nutrients. However, it is possible to resynthesize glycogen during exercise, during periods of low exercise intensity. You must have adequate CHO calories, and a very low exercise intensity (think of coasting downhill on a bike). This also has been found to only occur in endurance trained athletes. But as a trained athlete, you can recharge the stores of that precious fuel for exercise. So before long descents are periods of low intensity exercise, make sure to consume carbohydrate in order to maximize the potential for glycogen synthesis during exercise.

If you get behind on your nutrition and suddenly find yourself slowing down, your perceived exertion going through the roof, fear not, your race isn't over. Slow down, refuel and reassess your day. These are things you can do to help pull your race back together and finish with a smile on your face.